We consider the hypothesis that fundamental symmetries of quantum gravity
require correlations of primordial scalar curvature perturbations among world
lines to be consistent with causally-coherent entanglement within their
inflationary horizons. The angular power spectrum ${C}_ell$ of primordial
curvature on comoving spherical surfaces governed by this constraint has much
less cosmic variance than predicted by the standard quantum model of inflation.
The 2-point angular correlation function ${C}(Theta)$ is predicted to obey
new, exact causal constraints at $Theta>90^circ$, and an approximate analytic
model of ${C}(Theta)$ is constructed based on causal considerations. The
causal constraints and analytic approximation are shown to be consistent with
measured correlations of CMB maps on large angular scales, allowing for
uncertainties from the unmeasured intrinsic dipole and from Galactic foreground
subtraction. The absence of cosmic variance will enable powerful tests of the
hypothesis with better foreground subtraction and higher fidelity measurements
on large angular scales.
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